Mr Wright also confirmed that internal polling - before the leadership switch back to Kevin Rudd - showed Labor would be reduced to just 30 Lower House seats and Western Sydney would become a "Liberal heartland".

He said he briefed then-leader Julia Gillard on the polling, giving her the news "straight".

"She had amazing resilience, and not a fragile person,' he said.

"She was tough as nails and she deserved to get the truth and that's the way I did it."

But Mr Wright came down on the side of those in the party who believe that returning Mr Rudd to the prime ministership saved the party from that dire outcome.

"Kevin campaigned extremely hard during the 2013 campaign, he threw everything that he had at it and he did make a difference," he said.

He said the bounce in polling shortly after Mr Rudd made his comeback led him to think that the party could pull off an "unlikely" victory and that "in retrospect" the then-prime minister should have called an earlier election.

But he dismissed one of Mr Rudd's major policy announcements during the campaign - to cut company tax rates in the Northern Territory.

"I don't think that will be progressed too much further in the short term," Mr Wright said.

There have been reports that the policy was announced on the run, against advice from Mr Rudd's own policy experts and without consultation with ALP headquarters.

He also revealed that the leadership change prompted more than two-thirds of the party's campaign staff to quit because of a lack of "interest and willingness" to work for a Rudd victory.

"There were massive logistical issues and strategy issues that we had to deal with in a very tight timeframe," he said.

"Was it a perfectly-run, well-oiled machine campaign? No it was not.

"Did we hold it together? I think we did."

Mr Wright paid tribute to both former leaders and said it was up to Mr Rudd to decide if he would remain in parliament or not.